This is an application for 5 years of support from the Clinical Center at Georgetown University to continue participation in the ongoing multicenter Advanced Glaucoma Intervention Study (AGIS). It is the lead application for the study and is accompanied by applications from 10 Clinical Centers and a Coordinating Center. The principal goal of AGIS is to assess systematically the long-range outcomes of sequences of Interventions In eyes with primary open-angle glaucoma that have failed initial medical treatment. Between April 1, 1988 and April 30, 1991 AGIS has enrolled 600 eyes of 454 patients. Each eye has been randomly assigned to one of two intervention sequences: 1) trabeculectomy (T) followed by argon laser trabeculoplasty (ALT) should T fall and followed by a second T should ALT fail; and 2) ALT followed by T should ALT fall and followed by another T should the first T fall. The interventions are supplemented with medical treatment as needed. As of January 31, 1991, with follow-up ranging from 0 to 34 months, less than 1 percent of patients had been lost to follow-up and about 2 percent of visits had been missed. Data are being collected on visual function loss, intervention failure, complications, need for supplemental medical therapy, compliance with medical therapy, and quality of life. The prognostic value of ocular and non-ocular medical factors and personal factors is being studied. We plan to 1) continue patient recruitment until 790 eyes are enrolled, a goal that we expect to reach between April 1 and November 30, 1992, and 2) continue patient follow-up until November 30, 1996, so that follow-up will range from a minimum of 4 to 4 2/3 years (depending upon when enrollment is completed) to a maximum of 8 2/3 years. The Coordinating Center collects, processes, and analyzes study data and coordinates study activities. A Policy and Treatment Effects Monitoring Board supervises the conduct of the study and monitors study outcomes. Submitted with the Georgetown University lead application are: 1) the AGIS research plan, detailing study rationale, design, and methods, 2) study accomplishments to date, including examples of data analysis, and 3) plans for continued patient recruitment, follow-up, and report writing. The application describes the qualifications of the collaborators in this multicenter study and in particular, details the qualifications of the Georgetown University Clinical Center which consists of a parent facility and a satellite center. Between April 1, 1988 and April 30, 1991 the Georgetown University AGIS Clinical Center has enrolled 50 eyes of 39 patients; of these, the satellite center contributed 16 eyes of 13 patients.